This invention relates to an animal litter which forms a gelled agglomerate of the litter material and urine upon moistening of the material by the animal. The gelled agglomerates can easily be removed manually or with a simple implement such as a scoop.
Animal litters are in common use around the household for purposes of removing animal waste products and minimizing odor of such waste products. Periodically, physical removal of contaminated litter material is necessary. With conventional litters, physical removal of waste products often necessitates removal of the entire litter composition. Such physical removal can be unpleasant, time consuming, and expensive.
Excellent teachings directed to cat litters are seen in Stuart, U.S. Pat. No. 4,685,420, which has the same assignee as the present application, and is incorporated herein by reference. Stuart teaches an animal litter comprising a porous, inert solid substrate and a dry, particulate water-absorbent polymer. When animal urine contacts the litter of Stuart, the urine is absorbed by the water absorbent polymer and porous substrate to form a neat, gelled agglomerate of urine, polymer, and substrate particles. The gelled agglomerate has sufficient mechanical integrity such that it can be removed by itself from the litter box manually or by scooping. The litter remaining in the litter box after removal of the gelled agglomerates is clean and useful. According to Stuart, particularly preferred water-absorbent polymers include polymers produced by polymerization of at least one monomer selected from the group consisting of acrylic acid, methacrylic acid and alkali metal salts of acrylic acid and methacrylic acid.
Crampton et al., U.S. Pat. No. 4,657,881 relates a litter comprising compacted particles of a solid substrate and an additive. This additive may be capable of gelling or thickening water, and may be a water soluble polymer such as a cellulosic ether. The additive and the substrate, which is preferably clay fines, are mixed together and compacted into particles. Crampton et al. teaches that the addition of the additive markedly increases the absorbency of the compacted particles over that of substrate alone.
Arnold, U.S. Pat. No. 4,494,482, relates a solid absorbent pad for use in animal litter boxes. The pad utilizes a composition of a solid absorbent material and a water-insoluble organic or inorganic hydrogel. Urine deposited on the absorbent pad is absorbed therein. Suitable organic hydrogels include polyacrylates, hydroxypropylcellulose, and carboxymethylcellulose. The absorbent material and hydrogel is effectively encased by means such as tissue paper, polyethylene film, rayon sheeting, and nylon screen preventing removal of the urine.
Accordingly, there exists a need for an animal litter wherein urine is not only absorbed by the substrate particles, but is removable therefrom without disposing of the entire contents of the litter. Further, there exists a need for a litter utilizing additional types of water absorbent polymers wherein the urine is absorbed by the substrate and the polymer to form a gelled agglomerate having sufficient mechanical integrity such that the agglomerate can be removed from the litter box.